A modern security system often comprises a number of surveillance cameras. The surveillance cameras give the security personnel a possibility to monitor a large area, such as several floors in an office building.
When having a number of cameras, the appearance of the images from the number of cameras should preferably be substantially similar with respect to brightness, sharpness, etc., since this makes the work of the operator less tiresome. More particularly, for a human eye, it is less tiresome analysing a number of images having similar appearance, than analysing a number of images with dissimilar appearance.
When having a number of cameras, the cameras are most often placed at different places having different light conditions, which makes predetermined settings a non-optimal alternative. Further, the number of cameras may be different types of cameras with, for example, different types of image sensors, which even further make predetermined settings a non-optimal alternative.
US 2003/0234866A1 describes a practical real-time calibration of digital omnidirectional cameras in the areas of de-vignetting, brightness, contrast and white balance control. Novel solutions for the colour calibration of an omnidirectional camera rig, and an efficient method for devignetting images are also presented. Additionally, a context-specific method of stitching images together into a panorama or a mosaic is provided.